After extensive laboratory experiments, preliminary clinical trials have shown it is possible to obliterate cerebral aneurysms and arteriovenous anomalies by low-risk techniques that involve a simple arterial puncture instead of major brain surgery. Originally begun as a project using magnetically-tipped catheters to achieve these goals, other unique and promising techniques have evolved. These include the use of catheters and polytetrafluroethylene intravascular sleeves.